Incandescent lamp.



w. A. DARRAH.

INCANDESCENT LAMP. APPLICATION FILED JULY 31.1914.

Patented Jan. 1, 1918.,

' WWI mama: v am t WILLIAM AUSTIN DARRAH, 0F MANSFIELD, OHIO.

INCA NDESCENT LAMP.

Specification of Letters Patent.

Patented Jan. ll, 1918..

Application filed July 81, 1914. 4 Serial No. 854,362.

To all whom it may concern: I

Be it known that I, WILLIAM AUSTIN DARRAH, a citizen of the United States, re-

siding at Mansfield, in the State of Ohio, have invented certain new and useful Improvements in Incandescent Lamps, of whic the following is a specification.

This invention relates to incandescent lamps and while in the present state of the art, it is particularly applicable to the nonvacuum, or gas-filled lamps, it may also be applied to other types of incandescent lighting devices.

The object of this invention is to increase the efliciency of incandescent lamps by reducing the loss of heat by the continuous passage of relatively cool gas over the relatively hot filament, or radiating element of the lamp.

. This may be accomplished by surrounding the heated radiating element by a transparent envelop, or semi-envelop, of material which will safely withstand the temperatures to which the gases, heated by the radiating element, will subject it. The envelop may be shaped like an inverted cup opened at the bottom, or it may be entirely inclosed, in which case it may, if desired, be surrounded by an evacuated heat insulating space, or any modification of these shapes may be used.

It will be obvious that by thus retaining the gases, which are intensely heated in the presence of the radiating element, that the coolin effect which they exert upon the radiatlng element will'be materially lessened and the efliciency of the lamp will berproportionally increased. I

It is well known that any solid body in the path of the gases from the radiating element is normally rapidly darkened by a deposit caused bythe radiating element and probably composed of a mixture of tungsten and tungsten compounds in thecase of tungsten filament lamp and in general, by a mixture of a material which forms the radiator and compounds of that material.

Since the dark deposit is rather opaque,

its density rapidly increasing with the period of operatlon of the lamp, it will be obvious that this deposit would make it impracticable to operate a lamp equipped with an envelop, as here described, unless some means are provided to overcome the difficulties caused by the deposit. This, I have accomplished by coating the inside of the transparent envelop, or economizer, with a compound which, at the temperatures encountered under operating conditions, is able to combine with the dark deposit, the resulting material being transparent.

I have found that if the surface of the transparent economizer, which is exposed to the deposit, is coated with a fusible material containing a decolorizer, that the deposit may be absorbed as rapidly as it is formed, thus substantially reducing the light absorption which would otherwise take place. As there are many substances and combinations of substances which will accomplish this result, I do not wish to be confined to any single material or combination of materials for the active portion of the economizer, but for purposes of illustration, will describe a few of the substances which may be used. The particular material chosen will depend upon such factors as the position of the material; its operating temperature; the size, nature andtemperature of the economizer; the material of the filament or radiator; the nature of the gas present, and other factors.

It is Well known that tungsten and salts of tungsten in a borax bead in the oxidizing flame give a colorless, transparent bead. Microcosmic salt, and various other fluxes, (for the beads may be classed as fluxes), act in a similar manner. On the contrary if tungsten or salts of tungsten are heated in an inert or reducing atmosphere in these beads the resultant bead is colored. If, however, an oxidizing material, itself colorless, is added to the borax or other bead, then even if heated in an inert atmosphere the bead may be made colorless. As a speclfic example, potassium nitrite and borax properly mixed, and melted will give a transparent bead with metallic tungsten and its salts even in an inert atmosphere.

By way of illustration, if we have an electric lamp containing hot or vaporized tungsten in any form, such for example as a filament or electrodes, there must then be some disintegration of the hot body which will naturally'condense upon the cooler walls of the lamp, If, however, the deposlt falls upon a substance, as for example a borax bead containing potassium nitrate, it will be understood that while I have confined the description to tungsten and certain fluxes and compounds, yet the invention is much broader than this, and applicable to fluxes and agents equivalent to the oxidizing agent for-almost any material which may be used as a radiator. -I am aware that it is'old to add to a lampcertain halogen containing materials but it should'be noted that none of these function as the compound which I add directly to the light transmitting surface. In general terms the borax or equivalent may be called a flux and the oxidizing agent or its equivalent a decolorizer.

With a'tungsten filament in nitrogen, or an .inert gas of the argon series and a quartz economizer, I have found that potassium nitrite, or nitrate, previously fused at a temperature slightly higher than the operating temperature of the economizer, is satisfactory. This material may be somewhat improved by the addition of such fluxes as borax, boric acid, sodium silicate, or microcosmic'salt in various proportions.

Magneum nitrite will allow the operation of the economizer at still higher temperatures and at the proper temperatures, the various chlorates, peroxids, perborates and other oxidizing compounds are satisfactory. An addition of an alkali hydrate, previously fused, may be made to secure somewhat more rapid action. Boric acid is a very useful oxid for this purpose as a flux, espe cially when mixed with some of the more stable chlorates, oxids, perborates, etc. It will thus be evident that there are many combinations possible for accomplishing this result. The required properties of the ma- "terialbeingm'ainly, that it shall be lighttransmitting and shall be able to combine with the deposit from the filament with the aid of the temperature reached in operation to form a substance which is light-transmitting. It will be evident that, if properl-yf constructed, the entire economizer may be formed from the active material.

Referringto the drawings, Figure 1, is an elevation partly in section of one form of economizer applied to a lamp, while Fig. 2-

showsa modification of the economizer which, if desired, maybe surrounded by an evacuated space for heat insulation, or the 1 surrounding space may be filled with a gas.

In the figures, 1 represents the lamp base walls of the lamp bulb may serve as the economizer surface and be coated with the active material. Having fully described my invention, I wishto secure the following claims: v 1. A11 incandescent lamp having a surface containing material composed of flux and an oxidizing agent.

2. In an incandescent mitting surface containing fiisible material composed of a flux and an oxidizing agent.

- 3'. In an incandescent lamp, a surface adjacent to the radiator, said surface being coated with an oxidizing flux for tungsten.

4.- In an incandescent lamp, a pocket .for gases heated by the radiator, said pocket containing a flux material for absorbing andrendering light transmitting a deposit thereoncaused by said radiator.

lamp a light trans- 5'. In an incandescent lamp, a surface heated by the radiator, and containing flux for holding and renderinglight transmitting the deposit thereon caused by said radiator.

transmitting surface, a portion of which 6. In an-electric lamp, a radiator, a lightcontains a glass like bodj having the property of forming a. solid transparent compound with a deposit caused by the radiator.

7. In a gas filled incandescent lamp, a.

pocket for retaining gases heated by the filament, said pocket being coated with a flux for-eombining with and holding the deposlt thereon caused by the filament. '8. An electric lamp comprising a radiator, a transparent surface heated by said rad ator, and coated with a glass-like materlal containing compounds for combining withv a depos t thereand rendering transparent on caused by said radiator.

9. In an electric lamp a surface coated with a material containing a flux and a de- .colorlzer.

10. An electric lamp containing incandescent tungsten, a transparent container, and

a coating on said container ofa flux and a -'decolor1zer.

11. An electric lamp having a radiating element and a light transmitting surface containing a flux for said radiating element and a decolorizer for said radiating element,

12. In an electric lamp, a pocket for gases heated by the radiator, alight transmitting surface at the pocket containing a material; and a flux for absorbin and decolorizing the deposit from the radiator.

13. A coating for a light transmitting sur- In testimony whereof I afiix my signature face of anfielectric lamp, salid coating comin presence oftwo Witnesses. prising a ux material an a decolorizing material. WILLIAM AUSTIN DRAH. 5 14. In an electric lamp a light transmit- Witnesses: v ting surface composed of a flux and a de- .C., S. CHANCE,

colorizer. P. F. CHANGE. 

